In a beam mill stand, lower horizontal roll chocks are supported by a screw-up while upper horizontal roll chocks suspended on hooks from balance beams are urged downward by a screwdown. Also vertical roll chocks are supported by and moveable in transverse guide ways. Thus all four rolls are moveable, in use, to form a roll gap of desired section. It is desirable to remove or replace the four rolls and their chocks as a single stack. The aim being to reduce the down time when changing sets of rolls. As mentioned in the mill stand the chocks are separately supported, and it is not possible simply to let them all rest one on another because the upper rolls would rest on the lower rolls with consequent damage to them. In order to prevent such damage to the rolls, packers have been inserted both between the lower horizontal and the vertical rolls chocks and between the vertical and the upper horizontal roll chocks. These packers have to be inserted between the chocks with the stand in the mill line. This has been a laborious, time consuming and often dangerous operation.